[Cerowrt-devel] Latency Measurements in Speed Test suites (was: DOCSIS 3+ recommendation?)

Rich Brown richb.hanover at gmail.com
Fri Mar 20 09:50:13 EDT 2015

On Mar 19, 2015, at 7:18 PM, Greg White <g.white at CableLabs.com> wrote:

> Netalyzr is great for network geeks, hardly consumer-friendly, and even so
> the "network buffer measurements" part is buried in 150 other statistics.
> Why couldn't Ookla* add a simultaneous "ping" test to their throughput
> test?  When was the last time someone leaned on them?
> *I realize not everyone likes the Ookla tool, but it is popular and about
> as "sexy" as you are going to get with a network performance tool.
> -Greg

Back in July, I contacted the support groups at Ookla, speedof.me, and testmy.net, and all three responded, "Hmmm... We'll refer that to our techies for review." and I never heard back.

It seems to be hard to attract attention when there's only one voice crying in the wilderness. It might be worth sending a note to:

- Speedtest.net <support at speedtest.net> or open a ticket at: https://www.ookla.com/support
- SpeedOfMe <contact at speedof.me>
- TestMyNet <webmaster at testmy.net>

I append my (somewhat edited) note from July for your email drafting pleasure.


--- Sample Letter ---

Subject: Add latency measurements (min/max)

I have been using NAME-OF-SERVICE for quite a while to measure my network's performance. I had a couple thoughts that could make it more useful to me and others who want to test their network.

Your page currently displays a single "latency" value of the ping time before the data transfers begin. It would be really helpful to report real-time min/max latency measurements made *during the up and downloads*. 

Why is latency interesting? Because when it's not well controlled, it completely destroys people's internet for voice, gaming, other time-sensitive traffic, and even everyday web browsing. As you may know, many routers (home and otherwise) buffer more data than can be sent, and this can dramatically affect latency for everyone using that router. 

I'm asking you to consider implementing the web-equivalent of the "Quick Test for Bufferbloat" that's on the Bufferbloat site. (I'm a member of the Bufferbloat team.) http://www.bufferbloat.net/projects/cerowrt/wiki/Quick_Test_for_Bufferbloat

Please get back to me if you have questions. 

Many thanks!


--- end of sample ---

> On 3/19/15, 2:29 PM, "dpreed at reed.com" <dpreed at reed.com> wrote:
>> I do think engineers operating networks get it, and that Comcast's
>> engineers really get it, as I clarified in my followup note.
>> The issue is indeed prioritization of investment, engineering resources
>> and management attention. The teams at Comcast in the engineering side
>> have been the leaders in "bufferbloat minimizing" work, and I think they
>> should get more recognition for that.
>> I disagree a little bit about not having a test that shows the issue, and
>> the value the test would have in demonstrating the issue to users.
>> Netalyzer has been doing an amazing job on this since before the
>> bufferbloat term was invented. Every time I've talked about this issue
>> I've suggested running Netalyzer, so I have a personal set of comments
>> from people all over the world who run Netalyzer on their home networks,
>> on hotel networks, etc.
>> When I have brought up these measurements from Netalyzr (which are not
>> aimed at showing the problem as users experience) I observe an
>> interesting reaction from many industry insiders:  the results are not
>> "sexy enough for stupid users" and also "no one will care".
>> I think the reaction characterizes the problem correctly - but the second
>> part is the most serious objection.  People don't need a measurement
>> tool, they need to know that this is why their home network sucks
>> sometimes.
>> On Thursday, March 19, 2015 3:58pm, "Livingood, Jason"
>> <Jason_Livingood at cable.comcast.com> said:
>>> On 3/19/15, 1:11 PM, "Dave Taht" <dave.taht at gmail.com> wrote:
>>>> On Thu, Mar 19, 2015 at 6:53 AM,  <dpreed at reed.com> wrote:
>>>>> How many years has it been since Comcast said they were going to fix
>>>>> bufferbloat in their network within a year?
>>> I¹m not sure anyone ever said it¹d take a year. If someone did (even if
>>> it
>>> was me) then it was in the days when the problem appeared less
>>> complicated
>>> than it is and I apologize for that. Let¹s face it - the problem is
>>> complex and the software that has to be fixed is everywhere. As I said
>>> about IPv6: if it were easy, it¹d be done by now. ;-)
>>>>> It's almost as if the cable companies don't want OTT video or
>>>>> simultaneous FTP and interactive gaming to work. Of course not. They'd
>>>>> never do that.
>>> Sorry, but that seems a bit unfair. It flies in the face of what we have
>>> done and are doing. We¹ve underwritten some of Dave¹s work, we got
>>> CableLabs to underwrite AQM work, and I personally pushed like heck to
>>> get
>>> AQM built into the default D3.1 spec (had CTO-level awareness & support,
>>> and was due to Greg White¹s work at CableLabs). We are starting to field
>>> test D3.1 gear now, by the way. We made some bad bets too, such as
>>> trying
>>> to underwrite an OpenWRT-related program with ISC, but not every tactic
>>> will always be a winner.
>>> As for existing D3.0 gear, it¹s not for lack of trying. Has any DOCSIS
>>> network of any scale in the world solved it? If so, I have something to
>>> use to learn from and apply here at Comcast - and I¹d **love** an
>>> introduction to someone who has so I can get this info.
>>> But usually there are rational explanations for why something is still
>>> not
>>> done. One of them is that the at-scale operational issues are more
>>> complicated that some people realize. And there is always a case of
>>> prioritization - meaning things like running out of IPv4 addresses and
>>> not
>>> having service trump more subtle things like buffer bloat (and the
>>> effort
>>> to get vendors to support v6 has been tremendous).
>>>> I do understand there are strong forces against us, especially in the
>>>> USA.
>>> I¹m not sure there are any forces against this issue. It¹s more a
>>> question
>>> of awareness - it is not apparent it is more urgent than other work in
>>> everyone¹s backlog. For example, the number of ISP customers even aware
>>> of
>>> buffer bloat is probably 0.001%; if customers aren¹t asking for it, the
>>> product managers have a tough time arguing to prioritize buffer bloat
>>> work
>>> over new feature X or Y.
>>> One suggestion I have made to increase awareness is that there be a
>>> nice,
>>> web-based, consumer-friendly latency under load / bloat test that you
>>> could get people to run as they do speed tests today. (If someone thinks
>>> they can actually deliver this, I will try to fund it - ping me
>>> off-list.)
>>> I also think a better job can be done explaining buffer bloat - it¹s
>>> hard
>>> to make an Œelevator pitch¹ about it.
>>> It reminds me a bit of IPv6 several years ago. Rather than saying in
>>> essence Œyou operators are dummies¹ for not already fixing this, maybe
>>> assume the engineers all Œget it¹ and what to do it. Because we really
>>> do
>>> get it and want to do something about it. Then ask those operators what
>>> they need to convince their leadership and their suppliers and product
>>> managers and whomever else that it needs to be resourced more
>>> effectively
>>> (see above for example).
>>> We¹re at least part of the way there in DOCSIS networks. It is in D3.1
>>> by
>>> default, and we¹re starting trials now. And probably within 18-24 months
>>> we won¹t buy any DOCSIS CPE that is not 3.1.
>>> The question for me is how and when to address it in DOCSIS 3.0.
>>> - Jason
>> _______________________________________________
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